At a ministerial meeting in Brussels yesterday, sources from the organisation said they were considering a greater role for nuclear weapons in Nato military exercises, to fend off Russian threats.

Russia's rhetoric and actions have become much more aggressive recently – last week, President Vladimir Putin announced to the world that he was going to buy 40 new intercontinental ballistic missiles.

Before deciding how to act, Nato defence ministers must decide how seriously to take the threats – they may consider the risk to be small, in which case a large rise in nuclear activity would be unnecessary.

Both Russia and the US have significantly decreased their nuclear arsenals since the Cold War, and the west is in no rush to return to a nuclear arms race.

“The nuclear activities, the investments of Russia in new nuclear capabilities, and the exercise activities by Russia in the nuclear domain is part of the global picture where we see a more assertive Russia,” said Nato secretary-general Jens Stoltenberg at the start of the meeting. “We will not be dragged into an arms race."

Another Nato diplomat involved in the meeting said:

There is very real concern about the way in which Russia publicly bandies around nuclear stuff. So there are quite a lot of deliberations in the alliance about nuclear [weapons], but it is being done very slowly and deliberately. We need to do due diligence on where we are.